Synthetic resin containers are broadly used as package containers for various things such as drinks. Package containers containing easy-oxidizing contents such as beers must have gas barrier properties.
However, polyethylene terephthalate (PET) bottles which are most broadly utilized as beverage containers could not provide the gas barrier properties required by beers.
To provide the gas barrier properties to the PET bottles, generally, they have been produced to have a multi-layer structure including a PET resin layer and a gas barrier resin layer.
As a recent technique for providing a container with a bas barrier properties, there is a coating technique using chemical vapor deposition (CVD) in place of such a multi-layer structure.
Particularly, a technique referred to as diamond-like carbon (DLC) deposition can provide a package container with largely improved gas barrier properties.
The DLC deposition is disclosed in Japanese Patent No. 2788412, Japanese Patent Laid-Open Application No. Hei 11-256331, Japanese Patent Laid-Open Application No. 2000-43875, or the like. DLC films and their properties are described in detail in Japanese Patent No. 2788412.
Some of these documents disclose containers having their inner walls on which is formed the DLC film, and Japanese Patent Laid-Open Application No. 2000-43875 describes formation of DLC film on an outer container wall, but there is no concrete description relating to a machine for making such a container.
Moreover, consumers often feel uncomfortable when a DLC film is formed on an inner wall of container, especially when it contains a drink.